ISO 3690-2012 pdf download.Welding and allied processes – Determination of hydrogen content in arc weld metal.
ISO 3690 specifies the sampling and analytical procedure for the determination of diffusible hydrogen in martensitic, bainitic, and ferritic steel weld metal arising from the welding of such steels using arc welding processes with filler metal.
The techniques specified in this International Standard include collection of diffusible hydrogen via displacement of mercury or collection into a headspace filled with an inert gas such as argon. The amount of hydrogen collected is determined by measuring the displaced volume in the former and by, for example, thermal conductivity in the latter.
The temperature for collection of diffusible hydrogen is controlled to avoid thermal activation of non-diffusible hydrogen.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 14175, Welding consumables — Gases and gas mixtures for fusion welding and allied processes
ISOITR 17671-1, Welding — RecommendatiOns for welding of metallic materials — Pail 1: General guidance for arc welding
ISO 80000-1 • Quantities and units — Pail 1: General
3 Principle
Filler material is deposited on to a standard test coupon in a manner that ensures control of pertinent variables to produce a representative specimen for analysis. Subsequent storage and handling of the specimen is controlled to prevent premature loss of hydrogen. Finally, the specimen is transferred to a gas collection apparatus (mercury method) or to a suitable vessel filled with an inert gas (thermal conductivity method) and held for a penod of time at a temperature sufficient to quantitatively release the diffusible hydrogen into an evacuated gas burette or into the inert gas headspace, respectively. The amount of hydrogen collected is determined by measuring the displaced volume (mercury method) or by thermal conductivity. Finally, quantification of the mass of deposited metal or volume of fused weld metal enables calculations of diffusible hydrogen in deposited metal, LID, or diffusible hydrogen in fused weld metal, HF, to be made.
4 Test procedures
4.1 Production of weld specimens
4.1.1 Summary
The welding consumable to be tested is used to deposit a single weld bead, which is rapidly quenched and subsequently stored at —78 °C or lower until analysis. Cleaning and slag removal are performed on the chilled specimen.
4.1.2 Welding fixture
An example of a suitable welding fixture to provide uniform test pieces for the welding processes specified in 4.2 is shown in Figure 1. It is designed to hold the uniform test pieces securely in alignment during welding and, in particular, to ensure that unclamping upon completion of welding can be carried out in a single operation according to the conditions specified in 4.1.4 c). The surface temperature of the fixture shall be between ambient and 25 °C above ambient at the start of each test weld. The fixture may be water cooled to decrease the cycle time, The temperature of the cooling water shall be controlled to prevent condensation of water on the surface of the fixture between test welds.
For all welding processes, the test piece assembly is damped in the welding fixture using annealed copper foil as shown In Figure 1. The foil may be annealed repeatedly and quenched in water after each annealing. Oxide scale after annealing is removed by pickling with dilute nitric acid (10 % by volume) followed by washing with distilled water and drying.ISO 3690 pdf free download.